In general, amplifiers are used to increase the power of signals. For example, amplifiers can be used to convert low-power radio frequency (RF) signals into larger RF signals for driving the antenna of a transmitter. In such cases, amplifiers may be implemented as part of overall power amplifier used by an RF transmission system.
Power amplifiers tend to consume a significant portion of the total power consumed by a transmission system. Therefore, the power amplifier's efficiency (i.e., the power of the amplifier output signal divided by the total power consumed by the amplifier) is an amplifier quality that designers consistently strive to increase.
Another important amplifier parameter is linearity. In general, amplifier linearity is a measurement of how accurate the output signal is compared to the input signal applied to the input of the amplifier, particularly when generating high power. Unfortunately, many amplifier designs with high theoretical power efficiencies like, for example, widely used Doherty amplifiers, have relatively poor linearity. Therefore, there remains a need for amplifiers that provide both relatively high efficiency and relatively high linearity, particularity for high power RF applications.